This note contains spoilers for the book.

 

Alternate history, about the Manhattan Project.

Specifically, in this universe they figured out that centrifuges were the way to go, instead of committing to the gaseous diffusion plant that ended up providing only 5% of the refined uranium for the actual Little Boy bomb.

So they had The Bomb a year earlier, skipped the Trinity test, and just dropped it on Berlin. Missed Hitler, though (Intelligence is hard).

Very heavy use of real people as characters. In fact all but two significant characters are real, and the protagonist was Benford's father-in-law. Benford worked directly with a nubmer of the others, including Szillard and Teller.

And in fact what's fascinating about this book is the inside look (albeit somewhat fictional) at the early Manhattan Project, before New Mexico was important, and before the project was official and government-run. I found the adventures after the first bombing, when Karl ends up in Europe and even working as an agent (going to meet Heisenberg in Zurich) considerably less interesting.

The world resulting is perhaps unreasonably utopian, but who knows? Russia doesn't swallow all of eastern Europe, China doesn't go communist, and Israel is still created, but larger and with more reasonable borders, and the wars there don't happen. No discussion about how colonialism is going to be handled (the book has a last chapter jumping forward to 1963, so this should have come up).

People tend to forget the scale of death in World War II. There's a huge focus on the 6 million victims of the Holocaust, but that's a small part of the total, which Benford puts at around 29 million. The majority of them Allied citizens (Russia, and China; we tend to forget that since they didn't remain allies, or since they aren't white, or perhaps somebody found an even worse reason).

Very glad I red this.